H.O. is just an abbreviation for high output. It really means nothing. As far as building an engine, make sure you build one with the mass air set-up. Since your stang is an 84 you don't have mass air. I'd try to get a complete engine used with mass air and computer. That's why everyone is running so fast while attaining a good street car. The mass air and EECIV computer makes it possible. Speed density is o.k. with little bolt ons, but change the airflow like a small cam or such, the computer can't tell there's more airflow and the computer's tables are mixed up and the car is going to run crappy. Also your 84 engine does not have a roller cam. That is a big disadvantage. Try to rebuild an engine from 90-93. Make sure you research everything before you start buying. Good Luck!

During most of the model run of the 5.0 Mustangs Ford made 2 versions of the 302 HO and standard. In 84-85 the standard 302 was a CFI (throttle body injection) about 130 HP, earlier versions had feedback 2 barrel carbs. 86 - 91 were EFI motors many with the plenum pointing to the pass side those were 150 HP. At the least a milder cam, different computer calibration, possibly different head castings as well. Those motors were installed in Thunderbirds, LTDII, Crown Vics, Lincolns etc.. Trucks had their own versions all tuned more for torque but basically the same as the other 302's

The 302 HO was just that, higher output only in Mustangs, 85 Capri RS and Lincoln LSC's. We all know about the 82 - 95 Mustang 302 HO's

Some slightly tweaked CFI 302's were installed in LSC's and LTD II's (the "euro sedans") before the switch to EFI

What is my point, not sure, oh yeah, if you get a crown vic 302 it wont be good much more than a short block core, expect to junk the heads intake cam etc.

The non-HO motors have cast pistons with no valve reliefs-HO's had forged from 85-92 and hypereutectic from 93 on, corporate Ford lowflow heads rather than the E7TE's, a low lift and duration camshaft compared to the HO. The block is the only thing I'd consider using off one of these.

It all depends on the years, basically. There are quite a few differences between models, and even differences within models back in the early/mid 80's.

The HO motor is exactly what it says though. High output. It makes significantly more hp than the standard version.

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Originally posted by smokedchevy:

Since your stang is an 84 you don't have mass air. I'd try to get a complete engine used with mass air and computer. That's why everyone is running so fast while attaining a good street car. The mass air and EECIV computer makes it possible. Speed density is o.k. with little bolt ons, but change the airflow like a small cam or such, the computer can't tell there's more airflow and the computer's tables are mixed up and the car is going to run crappy. Also your 84 engine does not have a roller cam. That is a big disadvantage. Try to rebuild an engine from 90-93. Make sure you research everything before you start buying.

MAF is not the reason the 5.0HO is quick. The MAF system will cost you 20hp vs a SD system stock for stock.

SD is capable of accepting cams, heads, intakes, and many other mods with tuning. If you have everything tuned and the fuel pressure adjusted correctly the car will run fine with a solid combo. 88workcar is running low 12's, 11's on NOS with his SD LX 5.0. His combo consists of a Cobra inake, E cam (had the B cam), Edelbrock aluminum heads, and some other goodies. The whole SD can't accept mods is some fairy tale. Some people have more problems with their SD cars than others, it's probably all in keeping the car tuned up, and making sure everything is put together right.

Why 1990-1993? 1988(CA), 1989(all) were MAF cars. They did a mild cam revision along with the addition of the MAF system, but it basically didn't change anything. The 1987-1992 engines are basically all the same. 1993 got cast hypereutic pistons instead of the forged units, and if I had a choice, I'd stick to the forged units.

There's a good wealth of information in the above posts. I'll spare repeating it all over again to you, but these guys are right in what they're telling you. I'm just now finishing up putting heads/cam/intake on my non-HO motor in my coupe. I've had some major problems getting the pulleys to fit right (crank pulley has a different offset than the HO's). Also, the fuel rails were different. The FPR was on the opposite side, so I've had to buy/fabricate new fuel rails. It's pretty much been a major PITA, but the final results should justify it all.

Here's what i know about the HO engines compared to the non-HO:
HO engines originally came with the 351W camshaft, which had more lift and duration i believe (hence the 351 firing order), and later years used the 351 firing order, but with a roller camshaft (not sure when non-HO engines and 5.8's became roller cammed)
The HO came with valve reliefs as previously mentioned and forged aluminum pistons from '85 until '92 whereas non-HO were cast (as previously mentioned)
The HO engines came stock with Steel timing sprokets and double roller timing chains whereas the non-HO came with the silent type.
HO engines came with a reverse rotation water pump
HO engines came with better induction systems (all years) and better exhaust ('85+ for exhaust).
These are for the most part general statements but apply to nearly every year HO engine in most ways.
Hope this helped in some way.

just as a point, ive never known anyone to have a 302 that didnt last to damn near 200,000. of course if your looking to upgrade, the rebuild is never a bad idea,,, but just wanted to point that out.
as for the cam, you could probably swing a little larger lift than that happily. not sure what your trying to do with the car. your on the right track with the dual pattern though and the 112 lobe seperation should be great for idle.
Q